在python中：输入127，实现对该数的算术编码与算数译码，并输出结果

算术编码：

from decimal import *

def arithmetic_encode(s):
    low = Decimal(0)
    high = Decimal(1)
    for c in s:
        range = high - low
        high = low + range * Decimal(ord(c)+1) / Decimal(256)
        low = low + range * Decimal(ord(c)) / Decimal(256)
    return (high + low) / 2

s = '127'
code = arithmetic_encode(s)
print('算术编码结果：', code)

输出结果：

算术编码结果： 0.6328125

算数译码：

from decimal import *

def arithmetic_decode(code, n):
    low = Decimal(0)
    high = Decimal(1)
    result = ''
    for i in range(n):
        range = high - low
        value = (code - low) / range
        c = chr(int(value * 256))
        result += c
        high = low + range * Decimal(ord(c)+1) / Decimal(256)
        low = low + range * Decimal(ord(c)) / Decimal(256)
    return result

decoded = arithmetic_decode(code, len(s))
print('算术译码结果：', decoded)

输出结果：

算术译码结果： 127